Useful laboratory technique

Although not directly relevant to LENR , here is a HENR experiment that was deadly because not the slightest safety precautions were taken. It would not have been difficult to have remote controlled this deadly experiment with light duty stranded wire cables, pulleys, levers, perhaps an aluminum framework for the mechanics, and, of course, plenty of shielding at a distance for the experimenter.

Let the wise learn from this tragic account:

http://www.newyorker.com/tech/…-slotin?intcid=mod-latest

Alan, here is another weird one for you: my father-in-law was an icthyologist turned oceanographer. One of his first assignments just after graduating college was to be at the Bikini Island test (or another similar one, maybe Bravo). The observation ship he was on was positioned a distance deemed safe for the expected blast. The yield of the blast turned out to much much higher than expected. My FIL got a heavy dose of radiation. He is now 87 and pretty healthy.

Later, the same FIL was on an oceanographic vessel that just happened to be in the area of the Thresher disaster. A nuclear physicist happened to be aboard. The guy quickly drew a geiger counter circuit on a cereal box, rolled it up inside a pipe and sent the detector down to bottom of the sea looking for nuclear radioactivity. Other ships soon arrived. In anycase, the Thresher was eventually located.

When a person turns 70 as I recently did, the mind turns to passing on knowledge for the benefit of others. Hence this thread. So, here are a few trivial ones, but handy.

Chains are useful for a lot of things because they are infinitely flexible. Using small chain is good for attaching tools such as wrenches and screw drivers to an instrument or machine that needs that specific tool. Number 5 clock chain has links only about 11.5 mm by 6 mm. The links are hard steel that can be opened then attached to another link if needed.

When you need a hole through sheet metal, the drill bit often catches and the entire piece of sheet whirls around and is dangerous. Either be sure to clamp the sheet (with a space beneath to let the tip of the drill bit through, or, buy a hole punch. Harbor Freight sells sheet metal hole punches very inexpensively. Several punch sizes are included. Very handy.

As mentioned in the previous post, small gauge stranded wire, such as picture hanging wire is useful for remote control. For critical purposes, use clamps instead of just twisting the wire. You can buy pulleys and bearings at VXB bearings and many other places. While perusing a bearings site, be sure to look at Heim joints. They are like the classic ball joint on the steering apparatus of your car. They are available in tiny sizes suitable for instruments. Their utility is that if you think you can just mount a lever or push rod by a hole through it, it will snag and not be accurate. Heim joints solve that problem because they have two degrees of freedom. Heim joints are sold with both a left-hand thread varieties and right-threaded varieties. Put a right hand at one end of a push or pull rod and a left hand at the other end. Threaded rod between the two means that you can turn the rod thread to make an adjustable length connection between the two joints. You need to keep on hand a right hand and left hand tap to thread the rod. Aircraft controls invariably use Heim joints. Pilots want SMOOTH action and control. Researchers want the same on a mechanical connection. Basically Heim connections allow you to make a connection between two other rods that are not perfectly aligned. They never are perfectly aligned. The two degrees of freedom on the heim at each end allow the 3-D misalignments to be accommodated.

As with the misalignment to be accommodated between linear push/pull rods, there is also a need to accommodate the unavoidable misalignment between two rotating shafts. Just connect the two shafts with a third shaft with a universal joint (also called Cardan joint) on each end. It is necessary that the universal joints be phased so that the U on each end of the ending third rod is in the same plane as on the other end. Many a car mechanic knows this. Those who don't get an immediate complaint from a customer about a thumpiness to the ride.

An alternate to universal joints are easy to build rag joints. Cars use them for the steering connection. You can make your own by gluing together enough layers of cloth to make a connection disc, then make four holes around the edge of the disc. Then connect opposite holes to the same bar (or U) that goes to a rotating shaft. Do the same with the other pair of holes that go to the other rotating shaft. I sometimes use brass foil cut into a cross shape. Rag joints don't transmit a much power, nor are they good when there is huge misalignment. They are for small misalignments.

Still another way to connect two rotating shafts is to use a coil spring that fits over both shafts. Leave some distance between the shafts so there will be free coils. This is only for low power connections. Most lab instruments are low power. A spring such as a screen door closing spring is suitable.

All of these little tricks for connections for rotating shafts are needed for connecting an electric motor to your scientific instrument.

An inexpensive shaft bearing for smooth shafts is simply cut up a sheet of felt (available at Hobby stores) , oil the felt, wrap it around the shaft and mount it in a clamp to hold the felt and shaft combination. Alternatively make the clamp in two pieces and use oiled felt on the top and bottom. This works very well.

A similar trick can be used as a very light duty overload clutch. An oiled felt disk is placed between two disks, each disk on a different shaft. When overload occurs, the disks and felt will slip. The ancient teletype machines used exactly this trick , except that I seem to recall that it was a series of disks and felt disks plus a spring to keep them in contact. A motor continually rotated. When a "start bit" of the Baudot code came in, an electromagnetic would release the driven shaft. As the driven shaft rotated during the course of the code word, further bits would then be set by an electromagnetic as the shaft rotated. At the end, a "stop space" would de-energize the electromagnetic and the catch on the driven shaft would be caught and the felt slip clutch would start to slip until another code word arrived. In these modern times we just use a UART chip or the same built into the entire computer chip.

I think it was the cryogenic deuterium that caused the unexpected power of the blast.